EEB 2245 Exam 2 Study
Guide
taxon - Answer named taxonomic unit to which individual species or sets of species are
assigned; can be any category of classification
terminal taxon - Answer units that occur at the tips of a phylogenetic tree
node - Answer position on a tree where (3+) branches meet
branch - Answer connection between terminal taxon and a node or between 2 nodes of a
tree
dichotomy - Answer node on a tree that connects 3 branches
polytomy - Answer node on a tree that connects more than 3 branches
sister taxa - Answer terminal taxa that are each other's closest relatives
most recent common ancestor - Answer a taxa that at some past time split into two taxa,
each of which gave rise to one of the clades
root - Answer oldest node on the tree
Clade (monophyletic group) - Answer a group containing all known descendants of a
single common ancestor
paraphyletic group - Answer a group that contains some, but not all known descendants
of a single common ancestor
character - Answer feature, trait, or attribute of an organism
character state - Answer one of the possible variant conditions of a character
plesiomorphy - Answer an ancestral character state, originated prior to the immediate
common ancestor
symplesiomorphy - Answer a shared ancestral character state, shared by two or more
taxa that is inferred to have evolved in a distant common ancestor
apomorphy - Answer derived character state, originated in immediate common ancestor
synpomorphy - Answer shared derived character state
ingroup - Answer set of taxa that are the focus of interest for a phylogenetic analysis
, outgroup - Answer taxa included in the phylogenetic analysis that are more distantly
related to all members of the in-group than the in-group members are to one another
Number of taxa equals - Answer diversification minus extinction
Number of fossils found is proportional to - Answer the volume of sedimentary rock at
any given time
Pull of the recent - Answer the more recently a species appeared in geologic time, the
more likely it is to be alive today
True or False: There has been a qualitative change in diversity over time? - Answer True
Examples of qualitative changes in diversity over time - Answer Cambrian explosion
Age of Fishes
Age of dinosaurs
Age of Flowering Plants
Category most appropriate for estimating a quantitative change in number of taxa over
time - Answer Families, just the right size because its numerous and all members must
go extinct before a family is considered extinct
background extinction - Answer normal levels of extinction constantly occurring,
evidence for this rate to be declining
mass extinction - Answer Five marked mass extinctions in history
True/False: Background and mass extinctions are caused by the same factors - Answer
True
Cause of the mass extinction at the end of the Cretaceous - Answer Asteroid impact in
the Yucatan Peninsula
Evidence for mass extinction explanation at end of Cretaceous - Answer Rocks that date
66 may that are high in iridium across the globe (common in asteroids and comets)
What is likely the explanation for the other four mass extinction events? - Answer Habitat
and environmental phenomena
True/False: Plants have experienced mass extinctions - Answer No, little evidence for
this. Plants have many mechanisms for dealing with environmental stresses of that
nature
Sepkoski's three marine animal faunas - Answer 1. Cambrian
2. Paleozoic
3. Modern
Guide
taxon - Answer named taxonomic unit to which individual species or sets of species are
assigned; can be any category of classification
terminal taxon - Answer units that occur at the tips of a phylogenetic tree
node - Answer position on a tree where (3+) branches meet
branch - Answer connection between terminal taxon and a node or between 2 nodes of a
tree
dichotomy - Answer node on a tree that connects 3 branches
polytomy - Answer node on a tree that connects more than 3 branches
sister taxa - Answer terminal taxa that are each other's closest relatives
most recent common ancestor - Answer a taxa that at some past time split into two taxa,
each of which gave rise to one of the clades
root - Answer oldest node on the tree
Clade (monophyletic group) - Answer a group containing all known descendants of a
single common ancestor
paraphyletic group - Answer a group that contains some, but not all known descendants
of a single common ancestor
character - Answer feature, trait, or attribute of an organism
character state - Answer one of the possible variant conditions of a character
plesiomorphy - Answer an ancestral character state, originated prior to the immediate
common ancestor
symplesiomorphy - Answer a shared ancestral character state, shared by two or more
taxa that is inferred to have evolved in a distant common ancestor
apomorphy - Answer derived character state, originated in immediate common ancestor
synpomorphy - Answer shared derived character state
ingroup - Answer set of taxa that are the focus of interest for a phylogenetic analysis
, outgroup - Answer taxa included in the phylogenetic analysis that are more distantly
related to all members of the in-group than the in-group members are to one another
Number of taxa equals - Answer diversification minus extinction
Number of fossils found is proportional to - Answer the volume of sedimentary rock at
any given time
Pull of the recent - Answer the more recently a species appeared in geologic time, the
more likely it is to be alive today
True or False: There has been a qualitative change in diversity over time? - Answer True
Examples of qualitative changes in diversity over time - Answer Cambrian explosion
Age of Fishes
Age of dinosaurs
Age of Flowering Plants
Category most appropriate for estimating a quantitative change in number of taxa over
time - Answer Families, just the right size because its numerous and all members must
go extinct before a family is considered extinct
background extinction - Answer normal levels of extinction constantly occurring,
evidence for this rate to be declining
mass extinction - Answer Five marked mass extinctions in history
True/False: Background and mass extinctions are caused by the same factors - Answer
True
Cause of the mass extinction at the end of the Cretaceous - Answer Asteroid impact in
the Yucatan Peninsula
Evidence for mass extinction explanation at end of Cretaceous - Answer Rocks that date
66 may that are high in iridium across the globe (common in asteroids and comets)
What is likely the explanation for the other four mass extinction events? - Answer Habitat
and environmental phenomena
True/False: Plants have experienced mass extinctions - Answer No, little evidence for
this. Plants have many mechanisms for dealing with environmental stresses of that
nature
Sepkoski's three marine animal faunas - Answer 1. Cambrian
2. Paleozoic
3. Modern
